Stringed instruments, or chordophones, have been in existence for centuries. Their sounds are produced by striking, plucking, or rubbing strings made of vegetable fiber, metal, animal gut, or plastic, wherein the strings are displaced from a normal position of rest and caused to vibrate in a complex pattern. In nearly all stringed instruments, the sound of the vibrating string is amplified by the use of a resonating chamber or sounding board. Chordophones may be divided into four categories arranged according to the manner in which the strings are positioned in relation to the body of the instrument, particularly the resonating chamber.
The first category consists of instruments of the zither family, in which the strings lie parallel to and are of the same length as the resonating chamber. Well known examples include dulcimers in which the strings are struck, and psalteries in which the strings are plucked. A second category consists of instruments of the lyre family. A lyre is constructed from an oval, round, or rectangular sound chamber from which sound chamber two arms protrude joined at the top by a cross piece. The strings extend from the cross piece over the belly of the instrument and are connected to the belly by a bridge. The strings of the lyre are not normally stopped but are allowed to vibrate throughout their entire length when plucked by the performer. A third category consists of instruments of the harp family. Although the harp family exhibits an extraordinary variety of constructions, harps are all alike in that in all harps the strings are of unequal length and are fastened at either end to a frame that lies in the same plane as the strings. The modern orchestral harp, for example, is of triangular shape with the cross piece held nearest the player and bearing a hollow resonating chamber. The fourth category consists of instruments of the lute family, probably the most widely distributed family of stringed instruments in the world. Their characteristic structure consists of an enclosed sound chamber, or resonating chamber, with strings passing over all or part of the resonating chamber, and a neck along which the strings are stretched. The player moves his or her fingers up and down the neck, thus shortening the strings and producing various pitches. The string vibrations are transferred to the resonating chamber by a bridge; the resonator magnifies these vibrations and transfers them to the air.
The fiddle, one instrument of the lute family, can be distinguished from other members of the lute family in that it is generally played with a bow. The fiddle evolved into two groups; one group comprising relatively square shaped instruments held in the arms, known as the viola de braccia or "arm viol", and another group held between the legs, known as the viola de gamba or "leg viol." The former group may be further sub-classified depending upon the manner in which the instrument is held when it is played: either vertically or horizontally.
The violin family of stringed instruments are generally considered to be represented by a fiddle which is played in the horizontal position, specifically by holding the fiddle against the shoulder. During its history, the violin has been subject to modifications that have progressively adapted it to its evolving musical function. For example, the earlier violins were more deeply arched in the belly and back while the modern violins are shallower. Furthermore, in the nineteenth century with the advent of large auditoriums and larger concert halls and with the emergence of the violin virtuoso, the violin underwent its last major change in design. The bridge was heightened, the sound post and bass bar were thickened, and the body became flatter. In addition, the neck and the finger board were tilted backwardly placing the strings under greater tension, and, thus, giving greater pressure of the strings on the bridge. The result was a stronger, more brilliant and increased tone in place of the delicate, intimate tone of the violin of the eighteenth century. In addition to changes in the violin itself, the bow was redesigned to employ a slightly concave shape rather than the then existing convex shape; and, finally, a chin rest was added as well as shoulder rest.
Shoulder rests for use with violins and violas have been known for years, and served basically as a pillow-like member which accommodates and supports the instrument comfortably to the individual violinist's physical characteristics of shoulder and neck size. Such prior shoulder rests have had a number of deficiencies including a structure which limits the prior shoulder rest to being located in only a relatively few positions, so that the violinist usually had to compromise his or her comfort. Furthermore, some of the prior shoulder rests engaged a substantial portion of the underside of the violin thus partially absorbing and muffling the violin sound; such a structure affected the tonal quality and resonance of the instrument.